For most of a game of Starcraft, there is an interesting ongoing choice: Economy, Tech or Army.
Great thread covering this concept
You're balancing build order execution, scouting, reactions, harassment and teching, dynamically. It is very taxing and interesting, especially in ZvZ.
In the lategame we get a lot less of this however. For example, in TvZ, after you hit 3/3, sometimes you rebuild SCVs or make a minor adjustment, but it's hardly necessary to even look at your base for the rest of the game except to rebuild something a zergling/muta blew up.
(I recall a game where Bomber had 10-15 marines stuck in his main for 20 minutes and he never noticed, though the game was extremely close despite it.)
Basically, the lategame is just A(rmy) with some E(conomy) balancing. You expand as much as you think you can defend, but basically you're done with difficult, interesting decisions regarding tech unless you're going to tech switch (Jaedong...).
This is disappointing for players who really enjoy the base building, build order aspect of the game, as it fades out after the midgame a LOT. You get to want to tech switch out of boredom sometimes because your roach/hydra/viper army reached its final form 10 minutes ago.
I just think that some super late game upgrades should be added to make that phase of the game in LotV more interesting for players who really enjoy that aspect.
Ideally this would involve building and managing structures, but even just some super lategame upgrades would be nice.
Even if it just allowed upgrades to go up to 5/5, or had incremental speed boosts for some units, maybe even a pop cap increase upgrade. Something
edit:
I just want to emphasize, some players love the base building decision and execution aspect. FilterSc? Flash? Players of Offworld Trading Company? It was missing in C&C 4, and we sure felt its absence. It belongs more prominently in the lategame too, not just the early-mid.